#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
LL A,B,n;
LL getsum(LL x){
   return  (A+A+(x-1)*B)*x/2;
}
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   cin>>A>>B>>n;
   while(n--){
      LL l,t,m;cin>>l>>t>>m;
      if(getsum(l)-getsum(l-1)>t){
         cout<<"-1"<<"\n";
         continue;
      }
      LL down=l;LL up=(t-A)/B+1;
      while(down<up){
          LL mid=(down+up+1)>>1;
          if(getsum(mid)-getsum(l-1)<=t*m  )  down=mid;
          else up=mid-1;
      }
      cout<<down<<"\n";
   }
   return 0;
}
